Equipment for manufacturing laminated metal sheet

ABSTRACT

It is an object of the present invention to provide equipment for manufacturing a laminated metal sheet, which eliminates bubbles even in high speed lamination of 200 m/min or more and is excellent in productivity. In the equipment for manufacturing a laminated metal sheet according to the present invention, a metal sheet (1) is laminated with a resin film (3) on one or both side of it by lamination rolls (2), and a support roll (5) is disposed on projected beyond a straight line between the lamination roll (2) and a film roll (6) so as to impart tension to the film (3) when the film (3) is fed to the lamination rolls (2) from the film roll (6). Further, the support roll (5) is provided directly before the lamination roll (2) so as to satisfy the relation of L×V≦600 when the lamination speed is V (m/min) and the length of the resin film between the lamination rolls and the support roll is L (m).

FIELD OF THE INVENTION

The present invention relates to equipment for manufacturing a laminatedmetal sheet, which can effect high speed production of the laminatedmetal sheet and reduce bubbles generated in high speed lamination.

BACKGROUND OF THE INVENTION

In the field of containers for foods and beverages, laminated metalsheets which are formed by laminating a resin film to a metal sheet havebeen used in place of the conventional plated steel sheets and coatedaluminum sheets. So far, methods for manufacturing these laminated metalsheets have been known (Japanese Patent Laid-open Publication No.Hei-4-201237, for example). They are excellent in the respect that theyuse no solvent and no ovens for baking finish, differently from the caseof manufacturing coated metal cans.

The laminated metal sheets for containers use should satisfy variousrequirements, for example, good adhesion of a film to a metal sheetendurable to press-forming, deep drawing, ironing, or the like when theyare formed into cans and no disfigurement of the surfaces thereof sothat the resin film can be free from damages during forming. In thisregard, therefore, generation of bubbles in the laminated metal sheet isundesirable because the adhesion between the resin film and the metalsheet is decreased, the surface of the laminated metal sheet isroughened, which easily causes the surface to suffer damages duringforming, and further the appearance of the laminated metal sheet isdegraded, all due to the bubbles. Therefore, efforts have been madetoward preventing the generation of bubbles in the laminated metal sheetwhen it is manufactured.

Today, as the demand for the laminated metal sheets increases, it ismore required to increase lamination speed for the purpose of improvingthe productivity thereof. However, when the lamination speed is simplyincreased, a great quantity of bubbles generate, which is the reason whythe lamination speed is so far limited.

DISCLOSURE OF THE INVENTION

It is therefore an object of the present invention to solve the problemdescribed above and provide equipment for manufacturing a laminatedmetal sheet, which eliminates bubbles even in high speed lamination of200 m/min. or more and is excellent in productivity.

To achieve the above mentioned object, the equipment for manufacturing alaminated metal sheet according to the present invention includes asupport roll disposed on a contacting side of a resin film with alamination roll such that the support roll is projected beyond astraight line between the lamination roll and a film roll so as toimpart tension to the film when the film is fed to the lamination rollsfrom the film roll.

Further, it is also that a support roll is disposed on a contacting sideof a resin film with a metal sheet such that the support roll isprojected beyond a straight line between a lamination roll and a filmroll so as to impart tension to the film.

In addition, it is also that a first support roll for imparting tensionto a film is disposed on a contacting side of a resin film with alamination roll such that the first support roll is projected beyond astraight line between the lamination roll and a film roll and a secondsupport roll is disposed on a contacting side of the resin film with ametal sheet such that the second support roll is projected toward theside reverse to the projecting side of the first support roll.Otherwise, it is also preferable that a first support roll is disposedon the contacting side of the resin film with the metal sheet such thatthe first support roll is projected beyond the straight line between thelamination roll and the film roll and a second support roll is disposedon the contacting side of the resin film with the lamination roll suchthat the second support roll is projected toward the side reverse to theprojecting side of the first support roll.

Furthermore, the equipment for manufacturing a laminated metal sheetaccording to the present invention includes a support roll disposedadjacently before the lamination roll such that when the laminationspeed is V (m/min.) and the length of the resin film between thelamination roll and the support roll is L (m), the relation L×V≦600shall be satisfied.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an embodiment of equipment formanufacturing a laminated metal sheet according to the presentinvention.

FIG. 2 is a schematic view of another embodiment of the equipment formanufacturing a laminated metal sheet according to the presentinvention.

FIG. 3 is a schematic view of a comparative example for manufacturing alaminated steel sheet.

FIG. 4 is a chart showing the relationship between a lamination speedand an area ratio of bubbles.

BEST MODE FOR CARRYING OUT THE INVENTION

In the equipment for manufacturing a laminated metal sheet according tothe present invention, a heated metal sheet (1) is laminated with aresin film (3) on one or both sides of it by a pair of lamination rolls(2) so as to produce the laminated metal sheet (4). When the resin film(3) is fed to the lamination rolls (2), a support roll (5) is providedfor imparting tension to a film. This provision of the support roll (5)makes it possible to eliminate wrinkles from the resin film fed to thelamination rolls (2) even in a high speed lamination and further toeliminate wrinkles from the resin film carried on the lamination rolls(2). The wrinkles in the resin film just before the lamination, which isperformed at a high speed, cause bubbles to be much more generated inthe laminated metal sheet. Accordingly, if the wrinkles are eliminated,bubbles in the laminated metal sheet (4) can be reduced. The presentinvention is explained in detail below with reference to FIG. 1.

In FIG. 1, a plated steel sheet such as a chrome-plated steel sheet(tin-free steel) or a tin-plated steel sheet, aluminum sheet or the likeis used as the metal sheet (1). In general, the thickness of the metalsheet is 0.1 to 0.3 mm.

As the resin film (3), a single layer or multi-layers mainly composed ofa polyester resin (polyethylene terephthalate, polybutyleneterephthalate or the like), a polyolefine type resin (polyethylene,polypropylene or the like), a polyamid resin (6, 6-nylon or the like),or a polyearbonate resin or the like is used. An adhesive mainlycomposed of an epoxy resin may be applied to the above mentioned resinfilm (3) in advance. The general thickness of the resin film used in alaminated metal sheet for containers use is 5 to 50 μm.

As the lamination roll (2), a rubber-lining roll formed by coating ametal roll with fluororubber, silicone rubber or the like is used.

As the support roll (5), a rubber-lining roll formed by coating a metalroll having the same composition as that used for the lamination roll(2) with fluororubber, silicone rubber or the like, and also a metalroll plated with chromium or the like may be used.

Next, a manufacturing method for the laminated metal sheet is explainedin order. First, a metal sheet (1) such as a plated steel sheet or analuminum sheet is heated to an initial melting point of a resin that isa temperature at which the resin initiates melting, or higher. Normally,it is heated to a temperature higher than the initial melting pointmentioned above by 5 to 50° C. so that a melting layer of the resin filmcan be stably obtained. In the case where the resin film has been inadvance coated with the adhesive, the metal sheet is heated to atemperature higher than the temperature at which the adhesive iscompletely softened. Heating means for this case is, for example, aninduction heating device or a resistance heating device.

As explained above, the resin film (3) is fed to one or both sides ofthe heated metal sheet (1) and press-bonded to the metal sheet by thelamination rolls (2). The resin film and the metal sheet to be used areeach in a form of coil and the resin film and the metal sheet arecontinuously uncoiled, respectively, to be fed to the lamination rolls(2). The thus fed resin film is laminated onto the metal sheet by thepair of lamination rolls (2). The thus laminated metal sheet is thenquenched in water or the like.

In the industrially manufacturing equipment for the laminated metalsheet, since the resin film is thinner than the metal sheet, there occurwrinkles in the resin film when the film is guided to the laminationrolls. When the resin film having wrinkles is carried onto thelamination rolls, the wrinkles are set in the resin film because of therubber surface of the lamination rolls, which has no slidability. If abadly wrinkled resin film is laminated onto a metal sheet, a defectivelaminated metal sheet, which has the wrinkled resin film laminatedthereon, will be manufactured. Such defective laminated metal sheet iscommercially of no use. Therefore, in performing lamination, it has beencarefully executed to select a film with good configuration and adjusttension imparted to a resin film so that the resin film can be free fromthe occurrence of large wrinkles. Whereas, not so large wrinkles in theresin film are almost smoothed directly when the resin film is enteredbetween the lamination rolls, and therefore, wrinkles occurring in theresin film before the lamination have been not so much considered as faras the laminated metal sheet has no problem of the resin film aboutwrinkles. But after detailed investigation, it has been found that ifwrinkles occur in a resin film carried on the lamination rolls, alaminated metal sheet with such resin film is liable to involve bubblesand much more bubbles are generated especially in high speed lamination.

Although it is so far only guessed how the wrinkles of the resin filmaffect the generation of bubbles in the high speed lamination, resultsobtained from the observation on configurations of the bubbles generatedin the laminated metal sheet give the following thoughts. Namely, it isobserved that the bubbles of the laminated metal sheet (4) are typicallygenerated much in concaves of the surface of the metal sheet (1) havingroughness such as concaves and convexes, and they also typically havelongitudinal sizes ranging from 10 μm to some hundreds μm along thetravelling direction of the metal sheet. It is thought from thesetypical configurations, the bubbles seem to be generated in a case whereat the longest some 10 μm of a melt-softened resin film cannot smooththe concaves and convexes of the surface of the metal sheet directlyafter the resin film (2) enters a nip of the lamination rolls. It isthought that in the case where the resin film has wrinkles, the wrinkleswill be removed at the time when some μm of the resin film enters thenip of the lamination rolls, but the resin film does not come intocontact enough with the metal sheet until this time. Therefore, itshould be rather impossible for the melted resin to smooth the concavesand convexes of the surface of the metal sheet, resulting in easiergeneration of bubbles.

Next, a practical manner of eliminating the wrinkles of the resin film(3) is explained. In order that the resin film carried on the laminationrolls (2) should be free from wrinkles, the resin film being guided tothe lamination rolls has only to be free from wrinkles. Once the resinfilm without wrinkles is fed upon the lamination rolls, there is nochance to generate wrinkles in the resin film on the lamination rolls.Therefore, it is necessary to eliminate wrinkles from the resin filmdirectly until the resin film comes into contact with the laminationrolls. Among the various investigations, it is found to be effectivethat a support roll is provided for imparting tension to a film suchthat the support roll is projected upward beyond a straight line betweenthe lamination roll and the film roll (see FIG. 1). The support roll maybe projected downward to the same effect.

It is found to be also effective that a first support roll is providedto project upward or downward beyond the above mentioned straight lineand afterwards a second support roll is provided to project downward orupward, that is, toward the reverse projecting side of the first supportroll so as to impart tension to a film.

Further, it is found that if lengths of the resin film between therespective support rolls are shortened, the resin film can be free fromwrinkles. However, in a case where many support rolls (5A, 5B) aredisposed, this is practically unfavorable, taking into considerationspaces for the lamination lines and maintenance of the respectivesupport rolls. Further investigations have lead to the conclusion thatwhen two support rolls (5A, 5B) for carrying a film are disposed and thelength L (m) of the resin film between the lamination roll (2) and onesupport roll (5A) disposed adjacently before the lamination roll isshortened, the resin film can be almost free from wrinkles directlybefore the lamination rolls. It may be preferable that the length L ofthe resin film is made as short as possible, if the equipment allows it.Taking into consideration the fact that the quantity of bubblesincreases in accordance with increasing speed of lamination V (m/min.),the higher the lamination speed V, the length L of the resin film shouldbe shorter.

FIG. 4 shows suitable ranges of the lamination speed V (m/min) and thelength L (m) of the resin film between the support roll (5A) and thelamination roll. In FIG. 4, a case of the area ratio of bubbles being 8%or less is represented by a mark of ∘ as good (later described for thereason). Another case of the area ratio of bubbles being more than 8% isrepresented by a mark of × as inferior. The range defined by obliquelines in FIG. 4 is a suitable range for the lamination speed V and thelength L of the resin film, that is, a range as expressed by thecondition of L×V≦600. When the lamination speed V and the length L ofthe resin film satisfy the condition of L×V≦600, it is possible tomanufacture a laminated metal sheet having an allowable quantity ofbubbles.

The support roll (5A) adjacently before the lamination roll is disposedto come into contact with a side of the resin film to be contacted withthe metal sheet as shown in FIG. 2, or it is disposed to come intocontact with the side of the resin film to be contacted with thelamination roll as shown in FIG. 1. Either case has substantially thesame effect. However, when the resin film is coated with an adhesive,the support roll is disposed to come into contact with the side of theresin film to be contacted with the lamination roll so that the adhesiveof the resin film does not stick to the support roll. According to thepresent invention, two or more support rolls may preferably be disposedalong the travelling direction of the film. Because it is required toimpart uniform tension to the resin film in the width direction thereofand the two support rolls (5A, 5B) make it possible to impart thewidthways uniform tension to the resin film.

As described above, two or more support rolls (5A, 5B) are disposed toguide the resin film (3) to the lamination rolls (2), and the distancebetween the lamination roll (2) and the support roll (5A) disposedadjacently before the lamination roll is made short, in other words, thelength L of the resin film between the lamination roll and the supportroll (5A) is shortened, so that the wrinkles mechanically generated inthe resin film can be eliminated directly before the lamination rolls.As a result, it is also possible to reduce bubbles generated in theresin film. Further, as far as the length L (m) of the resin filmbetween the lamination roll (2) and the support roll (5A) disposedadjacently before the lamination roll (5A) satisfies the condition ofL×V≦600 with respect to the lamination speed V (m/min), it is possibleto manufacture a laminated metal sheet having a practically negligiblequantity of bubbles generated.

Next, examples of the present invention are described below.

EXAMPLE 1 to 3

A chrome-plating steel sheet (TFS, tin-free steel) having a thickness of0.2 mm and a width of 1000 mm was used as the metal sheet (1). Thechrome-plating steel sheet used in this case had a roughness Ra of 0.20μm and Rmax 2.2 μm. As the resin film (3), a film having a single layerof polyethylene-terephthalate having a thickness of 25 μm and a width of1000 mm was used. The metal sheet (1) was laminated with the abovementioned resin film on both sides of it. As the lamination rolls (2),silicone-rubber-lining rolls were used. The support rolls (5A, 5B) weredisposed as shown in FIG. 1 and metal rolls whose surfaces were platedwith chromium were used as the support rolls. The length L of the resinfilm between the lamination roll (2) and the support roll (5A) disposedadjacently before the lamination roll (2) was 1.5 m. The laminationspeed V was 400, 300, or 200 m/min.

EXAMPLE 4 to 6

The length L of the resin film between the lamination roll (2) and thesupport roll (5A) disposed adjacently before the lamination roll (2) was0.5 m. The other conditions were same as in Example 1 and the laminationspeed was 400, 300, or 200 m/min., respectively.

EXAMPLE 7 to 9

The support roll (5A) disposed adjacently before the lamination roll (2)was arranged so as to come into contact with the resin film (3) on themetal sheet-side and the length L of the resin film was 0.1 m. The otherconditions were same as in Example 1 and the lamination speed was 400,300, or 250 m/min., respectively.

COMPARATIVE EXAMPLE 1 to 3

The support rolls (5A, 5B) were disposed as shown in FIG. 1 and thelength of the resin film between the lamination roll and the supportroll was 3.0 m. The other conditions were same as in Example 1 and thelamination speed was 400, 300, or 250 m/min., respectively.

COMPARATIVE EXAMPLE 4

The resin film was directly fed from a coil-formed film roll to thelamination rolls without any support roll used as shown in FIG. 3. Inthis case, the length L' (m) of the resin film between the laminationroll and the film roll was 1.5 m and the lamination speed was 400 m/min.The other conditions were same as in Example 1.

The laminated metal sheets obtained under the respective conditionsmentioned above were observed with regard to the generation degree ofbubbles in the laminated metal sheets through a ultrasonic microscope.The area ratio of bubbles was obtained by observing an unit area of 1mm×1 mm of the laminated metal sheet, determining an area occupied bybubbles, and calculating an area ratio of the bubbles to the unit area.

The allowable area ratio of bubbles of the laminated metal sheet wasdefined on the basis of a critical range from when the coarse surface ofthe film resulting from bubbles generated in the laminated metal sheetis chipped off during drawing operation until when the chip-off becomesso remarkable. More specifically, when a laminated metal sheet, which isdrawn with a drawing ratio of 2.5, exhibits 8% or less area ratio ofbubbles, the film of a can so formed exhibits no remarkable chip-off.Therefore, the critical ratio of bubbles is defined as 8% by area ratio.

Wrinkles occurring in the resin film fed to the lamination rolls at thetime of lamination were visually observed.

Next, the results of the respective examples and comparative examplesare described. It is found from the results of Example 1 to 3 that theshorter the length L of the resin film between the lamination roll (2)and the support roll (5A) is, the less the wrinkles occur in the resinfilm guided to the lamination rolls and the lower the area ratio ofbubbles becomes as well. In Example 1 to 9, each lamination speed V andeach length L of the resin film satisfy the condition of L×V≦600, andeach resultant area ratio of bubbles is not more than 8%, which has nopractical problem. On the contrary, in any of Comparative Example 1 to3, the condition of L×V≦600 is not satisfied, more wrinkles occur in theresin film directly before the lamination rolls, and further, eachresultant area ratio of bubbles is higher than 8%, which renders thelaminated metal sheet so manufactured practically of no use. ComparativeExample 4 is a case where a support roll is not at all used. In thiscase, so much wrinkles are generated in the resin film fed to thelamination rolls and the resultant area ratio of bubbles of thelaminated metal sheet is so high as 25%. Clearly from this result, it isnecessary to provide a support roll.

The above mentioned results are summarized in the following table.

POSSIBILITY IN THE INDUSTRIAL USE

According to the equipment for manufacturing a laminated metal sheet ofthe present invention, wrinkles generated in a resin film fed tolamination rolls can be eliminated and the generation of bubbles in alaminated metal sheet can be suppressed in manufacturing laminated metalsheets for containers use. As a result, it becomes possible to performhigh speed manufacturing of the laminated metal sheets.

                  TABLE 1                                                         ______________________________________                                                     Lamin-                                                             Length ation Relation Generation of Area                                      of Resin Speed of V&L Wrinkles in ration of                                   film V(m/ V × L film (Visual Bubbles                                    L(m) min) (value) observation) (%)                                          ______________________________________                                        Example 1                                                                              1.5     400     600   little    7                                      Example 2 1.5 300 450 little  5                                               Example 3 1.5 200 300 little  4                                               Example 4 0.5 400 200 little  4                                               Example 5 0.5 300 150 little 3% or less                                       Example 6 0.5 200 100 little 3% or less                                       Example 7 0.1 400 40 no 3% or less                                            Example 8 0.1 300 30 no 3% or less                                            Example 9 0.1 200 20 no 3% or less                                            Comparative 1 3.0 400 1200 much 15                                            Comparative 2 3.0 300 900 much 11                                             Comparative 3 3.0 250 750 much  9                                             Comparative 4 No 400 -- too much 25                                            support                                                                       roll                                                                       ______________________________________                                    

What is claimed is:
 1. Equipment for manufacturing a laminated metalsheet by laminating a resin film onto one side or both sides of a metalsheet by lamination rolls, the equipment including a support roll whichis provided on contacting side of the resin film with the laminationroll such that the support roll is projected beyond a straight linebetween the lamination roll and a film roll so as to impart tension to afilm when the film is fed to the lamination rolls from the film roll,and further provided directly before the lamination roll so as tosatisfy the relation of L×V≦600 when the lamination speed is V (m/min)and the length of the resin film between the lamination roll and thesupport roll is L (m).
 2. Equipment for manufacturing a laminated metalsheet by laminating a resin film onto one side or both sides of a metalsheet by lamination rolls, the equipment including a support roll whichis provided on a contacting side of the resin film with the metal sheetsuch that the support roll is projected beyond a straight line betweenthe lamination roll and a film roll so as to impart tension to a filmwhen the film is fed to the lamination rolls from the film roll, andfurther provided directly before the lamination roll so as to satisfythe relation of L×V≦600 when the lamination speed is V (m/min) and thelength of the resin film between the lamination roll and the supportroll is L (m).
 3. Equipment for manufacturing a laminated metal sheet bylaminating a resin film onto one side or both sides of a metal sheet bylamination rolls, the equipment including support rolls, wherein a firstsupport roll is provided on a contacting side of the resin film with thelamination roll such that the first support roll is projected beyond astraight line between the lamination roll and a film roll so as toimpart tension to a film when the film is fed to the lamination rollsfrom the film roll and afterwards a second support roll is provided onthe other contacting side of the resin film with the metal sheet suchthat the second support roll is projected reversely to the projectingside of the first support roll, and further provided directly before thelamination roll so as to satisfy the relation of L×V≦600 when thelamination speed is V (m/min) and the length of the resin film betweenthe lamination roll and the support roll is L (m).
 4. Equipment formanufacturing a laminated metal sheet by laminating a resin film ontoone side or both sides of a metal sheet by lamination rolls, theequipment including support rolls, wherein a first support roll isprovided on a contacting side of the resin film with the metal sheetsuch that the first support roll is projected beyond a straight linebetween the lamination roll and a film roll so as to impart tension to afilm when the film is fed to the lamination roll from the film roll andafterwards a second support roll is provided on the other contactingside of the resin film with the lamination roll such that the secondsupport roll is projected reversely to the projecting side of the firstsupport roll, and further provided directly before the lamination rollso as to satisfy the relation of L×V≦600 when the lamination speed is V(m/min) and the length of the resin film between the lamination roll andthe support roll is L (m).
 5. The equipment for manufacturing alaminated metal sheet according to claim 1, wherein the lamination speedis 200 m/min. or more.
 6. The equipment for manufacturing a laminatedmetal sheet according to claim 2, wherein the lamination speed is 200m/min. or more.
 7. The equipment for manufacturing a laminated metalsheet according to claim 3, wherein the lamination speed is 200 m/min.or more.
 8. The equipment for manufacturing a laminated metal sheetaccording to claim 4, wherein the lamination speed is 200 m/min. ormore.